50,000 fans were given the chance to see the pilot online, while some television critics have also been given a preview of the episode.

However, Collins told Zap2It that the first episode has changed in a number of ways since then.

"I'm trying to tell people to watch the show when it airs," he said. "Because seldom has a pilot been so pre-screened, but there are added scenes that no-one has seen yet and won't see until it airs. Please watch it again, and watch it through to the very end."

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Collins added: "I was talking to [executive producer] Greg Berlanti the other day and saying, 'I hope you're getting the word out that people should watch it again, because critics have seen it'.

"God, there are so many shows that critics have to watch, if they feel they've seen a pilot, they're not going to watch it again. That's why I'm trying to urge them to do so, because it's a very different experience."

Meanwhile, a message from Berlanti's office confirmed that the pilot episode has been altered.

"We did recast Daphne's boyfriend and reshoot that, and there is the addition of the character of the Watcher, with a scene that will link him into the series," it read. "There are some other minor insert fixes."